Improvement in formers for segmentally screw-threaded insulators



s. OAKMAN.

Pate-Med Oct. 15,1872;

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SAMUEL OAKMA N, OF BOSTON, MASSACHUSETTS.

- IMPROVEMENT IN FORMERS FOR SEGMENTALLY SCREW-THREADED INSULATORS.

Specification forming part of Letters Patent No. 132,215, dated October 15, 1872.

OAsE B.

To all whom it may concern:

Be it known that I, SAMUEL OAKMAN, of Boston, in the county of Suffolk and State of Massachusetts, have invented a certain new and useful Mold for Telegraphic Insulators, of

which the following is a specification:

The Nature of the Invention.

The nature of my invention consists in constructing a device for forming a screw-thread on the inside of glass insulators. Said device, called a point, is made of an outside tube, the tube being slotted, and provided with screW-thread-bearing segments which fit into slots, and may be withdrawn radially and thus free. themselves from the molded glass. the segments being dovetailed to a coned spindle which fills the interior of the tube.

Description of the Drawing. Figure 1 is an elevation of the invention.

Fig. 2 shows the same in vertical section. Fig.

General Description.

Let A represent the outer tube or point, which forms the interior of the insulator.

This tube has slots E, Figs. 1 and 3, in which the segment thread-bearin g pieces 0 O 0 rest. These pieces 0 O O are dovetailed to the center piece D, which is made conical and so as to slide up and down in the tube A. As the pieces 0 O 0 have no longitudinal 1110111011; is evident that an upward motion of the center piece D will cause the pieces 0 O G to be drawn inwardly, as indicated by the dotted lines.

To form the screw in the insulator the point is inserted with the spindle D clear down, as shown in full lines in Fig. 2. When the glass has set the spindle Dis drawnup, which causes the pieces 0 G O to draw inwardly and thus free themselves from the inwardly-projecting thread on the inside of the insulator.

I claim as my invention The combination of the tube A, the spindle D, and. the segment-pieces O O 0, operating substantially as described, and for the purpose 1 set forth.

SAMUEL OAKMAN.

Witnesses:

A. HUN BERRY, FRANK G. PARKER. 

